[pacman-dev] Incremental package index support?

[Lukas Fleischer]

On Sun, Mar 24, 2013 at 11:26:04AM -0700, Anatol Pomozov wrote:
> Hi
> 
> On Sun, Mar 24, 2013 at 10:57 AM, Anatol Pomozov
> <anatol.pomozov at gmail.com> wrote:
> > Hi,
> >
> > I am an update junkie. I do "pacman -Suy" several times a day. One
> > thing I do not like with current pacman is that it redownloads whole
> > index file each time I update system.
> >
> > :: Synchronizing package databases...
> >  core                     104.4 KiB   104K/s 00:01 [######################] 100%
> >  extra                   1416.9 KiB   171K/s 00:08 [######################] 100%
> >  community               1916.6 KiB   204K/s 00:09 [######################] 100%
> >
> > It is 3.5M it total even if only just a few new packages were added.
> > Multiply 3.5M to number of users and you'll get a huge number. IMHO it
> > is waste of bandwidth and user time. From other side index is
> > incremental by it nature. Could pacman use index format that fits
> > incremental updates better?
> >
> > A naive proposal is to use compressed format for "full fetch" (e.g.
> > for users who did not update more than a week), and uncompressed
> > append-only index for incremental. On incremental update client sends
> > request to server "give me append file file starting from position XXX
> > till the end of file", so only delta from the last update will be
> > fetched. Then pacman applies the delta to client index.
> >
> > What do you think about this idea?
> 
> Ok, found pacman.conf option "UseDelta" that seems does what I need.
> BTW why it is not enabled by default? Isn't saving bandwidth a good
> thing?

I'm not sure whether "UseDelta" also affects package lists (rather than
packages only). Arch Linux does not support deltas on the server side
yet, see FS#18590 [1] for details.

[1] https://bugs.archlinux.org/task/18590